Paths of commerce:
Main centers of activity are in low Earth orbit, geosynch, the 2:1 resonant orbit, lunar orbit, the L-2 point (40,000 miles behind the Moon), and the lunar surface. (Drawing by the author). High-res version.

For power satellites to be built, for a major reach into space to go forward, there are three things that have to happen first.

The project must, of course, be technically feasible, well-understood, with no insurmountable difficulties. It must be advantageous from the standpoint of economics, offering benefits at an acceptable cost and being competitive with other ways of getting energy. But there is a third requirement, and advocates of new space projects have often made the mistake of ignoring it or failing to understand it. This is the requirement of politics.

To many space advocates, politics is rather a black art, difficult to understand. For nearly two decades, space advocates have lived in the shadow of a single day, a unique and bold political act. The day was May 25, 1961, and the man was John F. Kennedy. It was on that day that he went before the Congress with a statement: "I believe the nation should commit itself to achieving the goal, before this decade is out, of landing a man on the Moon and returning him safely to Earth."

Everything that has happened since, all the dreams and hopes and aspirations, has flowed from that day. But Kennedy was no idle dreamer; he was a solid realist, and his decision was not made in a vacuum. It addressed the felt national needs of the day. It did this so strongly that not till the late 1960s, not till a time very different from the one Kennedy knew, did the decision arouse great controversy. It was not the magic of Kennedy and the charisma of his Camelot that built and sustained the Apollo program. It is worth remembering that while he was alive, Kennedy was unable to get Congress to pass such reforms as Medicare or his civil-rights bill. Apollo went forward because it had the support of the country. Not just of the space enthusiasts, nor the science fiction fans, but the nation.

As the 1980 presidential elections begin to approach, the country is once again on the verge of yet another political change. Like so much else in our contemporary culture, the movement started in California. At every statewide election it is the practice there to submit to the voters a set of numbered propositions, or proposed new laws. In the June 1978 primary election, Proposition 13 called for massive cuts in the property tax, as well as reforms in the way new taxes could be levied. It passed with 65 percent of the vote. Overnight, pundits everywhere were pointing to this as the initial act in a taxpayers' revolt, a movement toward cuts in government budgets and significant changes in patterns of taxing and spending.

Should this trend go forward strongly, the next few years will not be easy for those who seek new federal initiatives in space. The emphasis will be on budget cuts, on eliminating waste, on recognizing the limits of government action. But so far from destroying hope for the power satellite, the spirit of Proposition 13 may actually pave the way for its rise.

For when this movement has gained its successes and written its insights into law, among its most significant contributions may be a clear understanding of the things governments can and cannot do well. Among the latter would be military interventions, massive attempts at social change, and control of the economy. Among the former are traditional functions like defense and the courts and schools, collecting taxes and distributing payment checks—and, on occasion, mobilizing the nation's energies for major technical efforts.

The Panama Canal, the Manhattan project, the Apollo program—in ten years these may loom larger in the nation's memory than they do today. They may be seen as rare occasions when the federal government displayed qualities all too uncommon, yet all too valuable: competence, skill, daring vision, sound management, the ability to move forward rapidly and to focus in on national goals. At the same time, it will be obvious that there are problems of energy and of our world standing that the nation can and should address. Our position in the world will be seen to rest on the new ideas and new things we can provide. In a world in thrall to the energy of Arabian oil, there will be many who will look to a solution in the energy of America's creative minds.

Today in Washington the power satellite is unattractive to many officials because it could only be built as a massive federal program. Ten years hence, this defect may be a virtue: It may be seen as one of the few major federal initiatives that could address significant national needs while going forward on time and within budget. The strict fiscal discipline of past NASA and aerospace budgets then will tell; it will be a solid guarantee of performance. It will contrast with the financing of social programs, whose budgets by law have been declared "uncontrollable."

In the official Washington of 1990, with its trillion-dollar budget, the power satellite may be seen as a way to demonstrate the competence of government in meeting our energy needs. It may be hailed as a way of bypassing the difficulties of commercial fusion and the environmental problems of coal and nuclear plants. Its proponents will use Kennedy's phrase, that it will "get this country moving again," while bringing forth the new generation of technical talent on which will rest our economic strength. Others will say that it would fire the country's imagination, lead us to look with hope to the new century rather than waste our strength in fruitless wranglings over the controversies of past years. Overseas, the export market may be justification enough, as the U.S. sells the works of its genius to balance its purchases of oil and raw materials. A world grown accustomed to U.S. communications satellites, computers, and aircraft may not long balk at getting power as well as data from American satellites. Nor may there be serious doubt as to the project's feasibility. With solid support from the technical community, with a public well familiar with the work of the space shuttle, with the continuing successes of a vigorous Soviet space program as inspiration, the power satellite may be accepted as naturally as was the interstate highway project in the 1950s. The ultimate presidential announcement may evoke a nationwide sigh of relief: "At last someone in Washington knows what he's doing."

Should there be such a national commitment, we will not want to piddle around half-heartedly with a handful of space shuttles. We will go forward to build the largest and best rockets we can conceive, just as with the Saturn in 1961. We will not be timid, nor will we shrink from the boldest of plans, but will seek the best means of addressing the question: How are the powersats to be built?

Even in an era of cheap space transport, it will be no mean feat to lift to orbit the megatons of propellant, materials, and supplies needed for a really serious powersat program. There is no doubt that at least the first few powersats will be built from Earth-launched materials. But once the powersats are actually operating, once the hopes of their advocates have been proven, there will be ample opportunity to seek lower costs and greater flexibility.

For all the awesome immensity of the Earth-launched powersat, it will appear in time to be quite conservative. There is a simple and straightforward line from Apollo and Skylab, through the shuttle and its early use in space construction, continuing on to more advanced shuttle-era projects built with the aid of a construction station, and on to the very large construction base to be used for production of full-size powersats. Even the long leap from shuttle-built communications platforms to true powersats introduces few truly new or untried procedures. It is more a matter of scale and organization, of operating many beam-builders and other equipment in a common program instead of merely a few.

Since an evolutionary approach can bring us so far, how much further can it take us? It is still too soon to answer this for certain. However, several years of study and analysis suggest that the ultimate answer will be "very far indeed" and that developments will proceed very much as has been foreseen by advocates of space colonization. These developments will arise out of the desire to lower the costs of powersats by building them from lunar resources.

This suggestion, that powersat costs might thus be reduced, originated with NASA official Jesco von Puttkamer in 1974 and gained the strong advocacy of Princeton's Gerard O'Neill. It was followed up by the economist Mark Hopkins at the 1975 Summer Study on space colonization and by Gerald Driggers at the 1976 Summer Study. But none of their work was truly convincing because their two powersat concepts, Earth-launched and lunar-derived, were designed and their costs estimated using entirely different ground rules. What was needed was a study that would look at the idea of a lunar-derived powersat with the same approaches and rules used for an Earth-launched design.

Precisely such a study got under way in April 1978 under the direction of Edward H. Bock at General Dynamics in San Diego. In contrast to the earlier Summer Studies of ten- and six- weeks' duration, this effort ran for ten months. It featured a seasoned team of professional engineers and consultants and had its overall management with the same NASA people who had managed Boeing's work on the Earth-launched powersat. These investigators thus were able to probe far more deeply than had the earlier studies.

Their first task was to design a powersat that could be built from lunar resources. This was a straightforward challenge; they took the Boeing design and broke it down to see what materials were to be used, then looked to see what lunar materials could be substituted. Their conclusion was that 91 percent of the mass of a powersat could come from the Moon. The remainder, some ten thousand tons per powersat, would consist of small quantities of silver, tungsten, and mercury, along with electronic
components and other complex devices. Interestingly, in 1976 Gerald Driggers had also proposed that 91 percent of a powersat's materials could come from the Moon.

Next, it was necessary to understand how the materials were to be transported and where the processing plants to convert lunar soil into useful materials would be located. For comparison, "Concept A" was the standard Boeing scenario for Earth launch. "Concept B" was right out of the 1975 and '76 Summer Studies. It called for a small group of moon-miners to operate a mass-driver, flinging bags of soil into space, where a mass-catcher would await their arrival. From there, the mass would be shipped to a processing plant in high Earth orbit and chemically processed deep in space. The products of this processing plant then would serve in construction of powersats, which then would be transferred down to their permanent location in geosynchronous orbit.

The particular high orbit chosen for the manufacturing was the so-called "2:1 resonant orbit" There the facility would go around Earth twice while the Moon was going round once; hence, "2:1." In this orbit it would swing from some 100,000 to 200,000 miles from Earth in the course of its two-week period.

"Concept C" put the manufacturing operations on the Moon. Lunar soil would be processed there, with only finished industrial products launched to space. Transport would be by rocket. The
rockets would burn hydrogen and oxygen: the oxygen obtained as a product of the lunar processing ,the hydrogen brought from Earth. These rockets would not tarry at any intermediate orbit, but would proceed directly from the Moon to a construction base at geosynch. There they would serve the same functions as cargo rockets from Earth, delivering the needed supplies.

"Concept D" was quite similar except that the fuel for the rockets would be powdered aluminum rather than hydrogen brought from Earth. Powdered aluminum had the advantage of being available from lunar soil.

Any one of these approaches would crisscross space with paths of commerce, turning the unexplored regions of pre-Apollo days into well-traveled domains of human activity. Concept A, of course, would have only two regions for this activity: low Earth orbit with its construction base and geosynch for final powersat assembly and maintenance. The two lunar-rocket options, Concepts C and D, would add two more regions: the lunar surface and lunar orbit. The latter would be the site for a refueling depot for rockets passing to and from the Moon.

Concept B would be the most ambitious; it would have six locations for activity. There would be the four noted, plus the 2:1 resonant orbit for the manufacturing center, and the L2 libration point for the mass-catcher. At this last location, a spacecraft can stay on station with little cost in propellant, since the centrifugal force of its orbital motion balances the combined gravitational pulls of Earth and Moon. L2 is located forty thousand miles above the lunar far side.

How many people would live at these various locations, and how long would be their tours of duty? The four main locations are low Earth orbit (LEO), geosynchronous orbit (GEO), the Moon, and the 2:1 resonant orbit (2:1). Then, according to the General Dynamics study, there would be the following:

PEOPLE NEEDED IN SPACE FOR POWERSAT CONSTRUCTION

Concept A
(Earth-launched)

Concept B
(Mass-driver)

Concepts C & D
(Lunar rockets)

People at LEO x tours per year

480 x 4

60 x 4

60 x 4

People at GEO x tours per year

60 x 4

60 X 6

1,200 x 6

People on Moon x tours per year

-

60 x 2

400 x 2

People at 2:1 x tours per year

-

1,400 x 2

-

Total people per year

2,160

3,520

8,240

Many of these jobs are in the area of maintaining the complex automated facilities. The basic processing and production equipment were assumed to be heavily automated. In addition, industrial robots were included for materials handling, machine feeding, and machine unloading. A total of 1,651 robots was estimated for these routine production tasks, or 3.8 robots for each human operator.

These crews would build one powersat per year, each one producing ten million kilowatts for each of thirty years. This production rate may be lower than what might actually happen, but it gives an indication of what might be expected. Concept B calls for the fewer people because the lunar mass processing and powersat construction take place at the same location, and because the crew quarters can be heavily shielded against radiation, thus prolonging the staytimes. The shielding would be of lunar soil, which is much easier to transport to the 2:1 orbit than to geosynch. Since Concept B is straight out of the world of space colonization, this comparison scores a point in its favor.

An important item for comparison is the weight of cargo to be lifted from Earth. The "startup
cargo" establishes the needed construction facilities and industrial plants, as well as the crew quarters. The "steady-state cargo," so many thousands of tons per year, is needed for the on-going production. The General Dynamics study gave the comparison:

CARGO TRANSPORT (THOUSANDS OF TONS)

Concept A

Concept B

Concept C

Concept D

Startup, 1,000's of tons

25.8

128.0

184.2

260.1

Steady state, per year

147.7

13.6

23.7

15.2

Total after thirty years

4,457

535

895

715

So there is another point on the side of the approach most favored by would-be colonizers of space.

Next comes the question of overall project costs. These costs would appear in several ways. There would be costs for research and development followed by program startup. In this phase there would be development and construction of the cargo rockets, as well as of the lunar or Earth-orbital industrial facilities. Then there would be production costs as the powersats appeared one by one. In addition, there would be costs for operating and maintaining the powersats, as well as the Earthside rectennas. The General Dynamics people gave cost estimates:

COST FOR THIRTY POWERSATS (BILLIONS OF 1977 DOLLARS)

Concept A

Concept B

Concept C

Concept D

Research and startup

70.586

121.756

135.476

145.760

Production (one per year)

656.476

280.415

320.250

296.755

Operations and maintenance

186.651

186.651

186.651

186.651

Total for thirty years

913.713

588.822

642.377

629.166

The operations costs were taken to be the same no matter how a powersat came to be. This comparison scores a most telling point for Concept B.

However, the bottom line in this table shows costs the size of the national debt. To be sure, economists know only too well that such costs are indeed like the nation's electricity bill for thirty years. The question is, at what cost must electricity from powersats be sold in order to cover expenses, if the costs are to be computed in a way a utility company might find reasonable? Note the comparison:

COST OF POWERSAT ELECTRICITY

Concept A

Concept B

Concept C

Concept D

Electricity cost, 1977 cents per kilowatt-hour

5.74

3.40

3.78

3.69

[Author's footnote: Startup and production costs are assumed to be divided evenly over the thirty powersats built one each year; each powersat is assumed to operate 95 percent of the time; and in each year of its operation, a powersat must generate revenues equal to I8 percent of its share of startup and production costs ("capital charge factor"). This last assumption follows standard practice in the utility industry. Operations and maintenance costs are figured on a pay-as-you-go basis. This method of cost estimating represents the views of the author and should not be regarded as reflecting the views of NASA or of its contractors.

These figures compare with costs of 3.5 to 4.3 cents per kilowatt-hour for future nuclear or coal-fired power plants, as estimated in 1978 by executives of Commonwealth Edison, Chicago's major utility company. According to Science, Edison Electric Institute reported 1977 figures for energy to be 1.5 cents per kilowatt-hour for nuclear energy, 1.8 cents for coal, and 3.7 cents for oil. In 1978 the figures were 1.5 cents for nuclear, 2 cents for coal, and 4 cents for oil. So the mass-driver approach scores one more point, the most significant of all, and wins the ball game.

Of course this is not the end of the matter, for ball games are played every day and few teams can win consistently. Similarly, one study does not a conclusion make, and many more studies will be in order before we will really be sure we understand the best way to build powersats. For instance, it is possible that this conclusion was influenced by internal NASA politics and the fact that the study was managed by the Johnson Space Center and not the Marshall Space Center.

NASA-Johnson and NASA-Marshall are two of the largest space centers, and their people have done yeoman work in the Apollo, Skylab, and Shuttle projects. In recent years their senior managements have increasingly felt that their centers' futures would depend on getting a large share of the action in any power satellite effort. Thus, NASA management has not given responsibility for powersat studies to any one center, but has allowed each center to pursue its particular design approach. So it was, in 1977, that Johnson contracted with Boeing and Marshall with Rockwell
International Corporation to carry out major studies.

The Boeing approach, discussed in Chapter 7, called for the powersat to be built in the shape of a single flat slab with transmitting antennas at each end. Power would be generated by silicon solar cells. The principal construction operations would be in low Earth orbit, where the construction base would build each powersat in eight sections resembling the leaves of a dining-room table. Each section (two of them would carry antennas) then would be fitted with ion-electric rocket engines and fly under its own power to geosynch. The ion engines would use electricity to eject atoms of argon at very high speeds, some 225,000 feet per second, to produce thrust.

Activities at geosynch would be strictly limited. Because each powersat section can produce much more power than it needs for the electric rockets, many of its solar arrays would be rolled up like window shades. The few crew members at geosynch would unfurl the arrays, causing the powersat sections to spread sail like a clipper ship. As each section arrived, at forty-day intervals, it would be joined to the others. A completed powersat would be activated by a ground station.

In contrast, Rockwell's design called for the use of huge mirror reflectors that concentrate sunlight on the solar cells. The reflectors would not be of silicon, but of a different material, gallium arsenide. The most unique feature of Rockwell's approach was that the main construction would take place in geosynch. The largest work crews would live there, and the powersat would be built as a single unit rather than piecemeal.

Both NASA-Johnson and NASA-Marshall agreed on the need for a transfer rocket, a Personnel Orbit Transfer Vehicle, to take people and their supplies to and from geosynch. It would be powered by hydrogen and oxygen brought from Earth. To get cargo from the Earth to low orbit, both centers agreed on the need for the huge cargo rockets, though they differed as to the best designs. For transporting cargo from low orbit to geosynch, the Marshall designers proposed an immense solar-powered Cargo Orbit Transfer Vehicle. Looking like a huge box kite, it would be fitted with solar panels and ion-electric engines to shuttle slowly and majestically between the two orbits. The need for several hundred workers in geosynch, rather than just a few dozen, turned out not to be a major problem; it would not significantly increase costs.

Clearly, no serious choice could be made between these approaches, or one of the NASA centers and its contractor would be left out. There was an attempt to come up with a powersat that would combine the best features of both. It ended up by assigning responsibility for major items of effort between Johnson and Marshall, in the fashion of eenie-meenie-miney-mo, or of "one for you, one for me." The resulting hybrid was called the "camel," a camel being defined as a horse designed by a committee. Few people within NASA took it seriously, and the likelihood was that Johnson and Marshall would pursue their approaches more or less independently.

If the powersat construction were to take place in geosynch, then it could be easier to bring in lunar materials by means of rockets from the Moon. There would be the need for an elaborate lunar base capable of producing rocket fuel and of turning lunar soil into industrial goods. But in the transition from Earth resources to lunar, life at the geosynch construction base would go on as before. The main difference would be that the cargo rockets would arrive from the Moon, not the Earth. This indeed is the scenario which Ed Bock would have studied if his funding had come from Marshall and not Johnson. It could have meant a decided fillip to Concept C or D.

However, this proposal really is not at all likely. At eighty-five hundred tons, the Boeing construction base would be scarcely heavier than a section of the powersats it would build, so that it could easily be moved to higher orbit. By spreading solar arrays like sails, and by installing ion drive,
this base would be only slightly more difficult to fly to the 2:1 orbit than to geosynch. It could then serve as the construction site for powersats, as in Concept B. Even more important, while still in low orbit it could be fitted out with its materials-processing equipment. It will be quite important to assure the proper functioning of this chemical processing plant in space, and everyone concerned will breathe easier if help is close at hand when things go wrong. And low Earth orbit is a lot closer than the Moon.

So this would continue the cautious, conservative, step-by-step approach. Bit by bit, the low-orbit construction base would receive its processing plant equipment, and with the necessary tests and checkouts, its reliable operation would be assured. It would not process lunar soil at first, but would be tested using lunar-like sand brought from Earth. One wonders what some senators will say when they learn that a huge cargo rocket has lifted off from Cape Canaveral carrying a five-hundred-ton cargo of crushed gravel.

Several hundred people will work at the processing plant, which will be highly automated. As far as possible, the processing will involve continuous flow, and the plant will be set up to run like a modern oil refinery or chemical company. The comparison is instructive. In December 1978 some sixty thousand oil-refinery workers walked off the job to strike for higher pay. But the refineries were so highly automated that they easily kept running under the control of the strikers' supervisors. In a long strike refinery equipment would have suffered for want of maintenance. But the strikers, finding their absence made little immediate difference, soon went back to work.

Once there is a fully functioning manufacturing and construction base in the 2:1 resonant orbit, it will be a latter-day version of Detroit's River Rouge plant, which takes in raw iron ore and turns out complete autos, all at one location. The space center will receive unprocessed lunar soil at one end and turn out a finished powersat at the other, ready to fly on ion engines down to geosynch.

The step-by-step completion of this center will finish what by far will prove to be the most difficult job. The remaining problems will mostly be solved on the Moon or near it. By comparison with the powersat project, and with the development of the manufacturing center, these efforts will seem minor. They will have much more in common with some of the more ambitious lunar-exploration programs proposed for the post-Apollo era of the 1970s. These efforts will provide for the actual shipping of lunar resources from the Moon to the 2:1 center; and in the most difficult parts of the problem there are solutions that are not only feasible but downright elegant.

The first of these problems involves the sensitivities at launch. The mass-driver acts like a cannon or catapult, and cannon often miss their targets. The payloads to be launched will be mere bags of soil, flying without guidance or course correction once away from the Moon. The target they must hit is the mass-catcher, forty thousand miles away near the L-2 point, yet only three hundred feet wide. This is such a difficult problem in aiming that if the payloads are launched with a velocity error of only a few microns per second (the speed of a swimming bacillus), they would be expected to miss. Few marksmen have ever faced such a problem.

The problem was studied during a 1976 summer study on space colonization of which I was a part and which was headed by Brian O'Leary, a former astronaut. The solution used my discovery of a new effect that amounted to a kind of focusing. Payload flight paths making use of this effect came to be known as "achromatic." [Author's footnote: In a camera, achromatic lenses bring light of different wavelengths to a common focus, Similarly, achromatic trajectories bring payloads launched with different velocities to a common target.] Using achromatic trajectories, there could be a launch velocity error of as much as ten centimeters per second, which would be easy to achieve. The payload would have a miss distance at L-2 of only twenty meters. Over the next year and a half, while I held a research fellowship in Germany, I went on to study these achromatic trajectories in detail. It turned out that this effect led to a complete understanding of the problem of lunar mass transport. In particular, the mass-catcher could always maneuver so as to be reachable via achromatic trajectories.

The mass-catcher represented the second major problem. The earliest suggestion for its operation dates to a NASA-Marshall report of January 1975, "Space Colonization by the Year 2000: An Assessment." That report pointed out that even if materials were launched from the Moon by mass-driver, it would be no mean feat to catch them:

There is nothing simple about catching [the stream of lunar rock]! . . . As ridiculous as it sounds, the best mechanism that could be devised in this analysis is a large funnel with reaction engines (possibly electric ion engines supplied with solar power). And even then the aim from the lunar surface must be extraordinary.

Without being aware of the Marshall work, at the 1975 Summer Study on space colonization I also suggested that there should be a mass-catcher and recommended it be in the shape of a large cone-shaped bag. But what was not understood was how payloads would actually be captured or caught when they hit the bag. They might just bounce out and be lost.

Help came from an unexpected quarter. In Tucson, Arizona, astronomer William Hartmann was studying what on the surface would look like a totally different problem: the origin of the planets. For years, planetary scientists had agreed that the planets must have been built up from many tiny rocky bodies, or planetesimals, which came together and stuck. But they could not understand how such bodies could have stuck together when colliding. It was much easier to believe they would have rebounded from each other like billiard balls.

In his laboratory Hartmann found that this assumption was not so. Such colliding bodies would tend to chip and fragment, forming quantities of dust or sand, which would cling to their surfaces. The layer of dust, called a regolith, would act as a shock absorber. It would absorb the impact of another body, and the feeble gravity of small planetesimals then could hold them together. Hartmann found that even thin layers of regolith would be quite adequate as shock absorbers.

It was easy to see how the same thing could happen in a mass-catcher. Bags of lunar soil would split open when they hit the catcher, and their contents would form a new regolith. When other bags hit, their impacts would be absorbed. Then a modest rotation of the bag would provide artificial gravity to hold everything in place.

From there it would be easy. When the catcher became full, it would accelerate forward while slowing down the spin of the bag, till its contents collected in a compact mass. The caught mass could then be packaged by the simple technique of pulling drawstrings to enclose it in a flexible container, as if it were so much dust collected in the bag of a vacuum cleaner. The catcher then would back away, releasing this large cargo into free flight. It would loop round the Moon, then escape into a high orbit of Earth.

The cargo then would go to the space manufacturing center in 2:1 resonant orbit. While I was consulting for Brian O'Leary in 1976, I also was wondering about this problem and found that the 2:1 orbit was the stable orbit most convenient to reach in this way. Of course, the cargo would not go directly to the center, but would merely pass in its vicinity. So a rocket-powered craft known as the terminal tug would be based at the center to go out and retrieve the large bag of lunar soil.

The bags could well run to a hundred thousand tons—the capacity of a seagoing ore carrier. It seems absurd to speak of handling such loads with mere rockets, but it's not. The cargoes will pass so slowly by the center that retrieving them will call for propellant tanks of quite modest dimensions: twenty meters diameter for the hydrogen, fifteen meters for the oxygen. A single flight of one of the large cargo rockets will carry the needed hydrogen from Earth to orbit.

The mass-catcher will be a most curious type of hybrid since it will have two distinctly different propulsion systems. Its hydrogen-oxygen rockets will take it from the 2:1 center to 2, as well as, permit it to maneuver near the 2:1 center in order to retrieve the cargoes. These rockets will also serve for the "ullage" maneuver, which compacts caught mass in the catcher bag so that it can be packaged. For the continuous maneuvering near L-2 during catching operations, it will have a second system: an electric propulsion drive. The power plant will almost surely be nuclear, since it is a safe prediction
that some payloads will miss the catcher. These would rip solar panels to shreds, but a nuclear reactor can be protected from damage.

With this, the roster of spacecraft and systems is complete. It is a rather impressive list:

Cargo rockets, to carry some five hundred tons of payload from Earth to low orbit.

An advanced version of the space shuttle to carry seventy-five people to and from low Earth orbit.

Personnel Orbit Transfer Vehicles to carry people as well as small priority cargoes. These provide connecting service between low Earth orbit, geosynch, the 2:1 orbit, and a low orbit of the Moon.

Cargo Orbit Transfer Vehicles, solar-powered and with ion drive, to carry large cargoes from low Earth orbit to the 2:1. These may also tow complete powersats from the 2:1 to geosynch on the return leg.

Space propellant depots, in low Earth orbit, geosynch, low lunar orbit, and at the 2:1. They will be capable of liquefying oxygen and perhaps hydrogen, so that these propellants can be stored indefinitely.

A maintenance and repair center for the powersats in geosynch.

The space processing and manufacturing center at the 2:1 orbit.

Lunar ferry rockets, to shuttle between an orbiting lunar station and the site of the mass-driver.

The mass-driver and lunar base, with a mine for lunar soil.

The mass-catcher.

And, not to be overlooked, the powersats. Most of them will be in geosynch.

Most of these facilities will call for space crews. There will be groups of perhaps a few hundred people living in the powersat maintenance center in geosynch, shuttling to and from the immense craft that will be in their care. A few dozen will live at such lonely outposts as the Moon and the four refueling depots. The true centers of the project will be the locales having the largest numbers of people: geosynch and the 2:1. Studies at Boeing propose that the powersat maintenance center have
480 people on ninety-day tours of duty. Such a work force could perform needed services for forty powersats each year. At the 2:1 center would be the 1,400 people on six-month tours.

Wherever there would be need for space crews, there would be crew modules to live in. The project managers will like such modules, perhaps more than will their inhabitants, because they are convenient. They can be built, fitted out, carefully tested, and proved on Earth. Then it is a straightforward matter to lift them to space. Even large one-hundred-person units fifty-five feet in diameter will fit neatly into the cargo bay of a single cargo rocket. While such modules will have far from identical internal layouts and systems, there will be enough similarity to make them fairly easy to maintain. They will readily be grouped in clusters, and if more are needed it will be simple to bring them up.

In the small stations at low Earth orbit and low lunar orbit, as well as in geosynch, the modules will be of the simple type described in the last chapter. Quite likely they will lack both radiation shielding and artificial gravity, at least for a while. On the Moon the modules will have coverings of lunar soil for protection both against radiation and nightfall: Outside their snug security, temperatures will rise and fall through a range of four hundred degrees. The most elaborate modules will be at the 2:1 center. There it will be possible to surround them with thick coverings of lunar sand for radiation protection. Also, like weights at the end of a barbell, modules will be rotated in pairs for much-desired gravity.

For all that, life at the 2:1 center will still be a far cry from the golden luxuries predicted for the Stanford torus space colony. The brief tours of duty and frequent crew rotations, the dependence upon
supply flights from Earth, the cramped submarine-like surroundings will all be much more like Skylab. At that point, space colony buffs may be forgiven if they feel their dreams are as far as ever from realization.

Yet it is always darkest before the dawn. It is precisely then that the influences that can usher in the first true space colony will begin to grow.

By providing shielding and artificial gravity, people will be able to serve many tours of space duty without harming their health. Yet few will want to. The recreation opportunities will be limited, the artificiality of the surroundings overwhelming, and the chance for normal family life virtually nil. Life in the modules, service in the powersat project will be very much an adventure for the young. There will be many who will seek to spend a few years of their careers this way, collecting their high salaries while serving a few tours of duty in space. Then, in the words of a Continental Army recruiting poster of 1776, "he may, if he pleafes return home to his friends, with his pockets FULL of money and his head COVERED with laurels."

The transient nature of space crews will create the need for a huge continuing investment in recruiting and training. As the project grows and expands in space, the Earthside training centers will
have to develop apace. There will be an enormous waste of talent and experience as people come and go without staying long. Many good people will leave the project just as they are at the point of their most significant contributions. Worse, a shortage of good people may actually delay needed expansion and growth.

It bids fair to imagine that after a few years the glamour and excitement of being a space worker will lose some of its attraction. Potential employees may look on space as merely one more of a variety of interesting and challenging ways to spend part of their careers. There may also be a problem if many space jobs call for skills and types of work not easily transferred back to Earth. The project veterans then could face the unpleasant choice of remaining with a space job that has become an inconvenience or risking unemployment by leaving. This possibility will become especially problematic as space jobs grow increasingly complex and specialized. There may be an echo of the early-1970s recession in the aerospace industry, when veteran employees often were told they were "overqualified" when they sought work outside that industry.

As any senior powersat manager will say, the most important resource will not be the metals of the Moon or even the robots and other complex equipment. The most important resource will be the project's people, and it will be quite important to keep the good ones with the project. As with any other effort calling for highly trained and skilled people, it will be very important to develop a solid core of career-minded individuals willing to live in space and to make it their home. This will bring other benefits as well. Crew members at the lunar base or at the geosynch maintenance center or refueling outposts will work better if they regard space and not Earth as their home. In the same way that many sailors regard the sea as home, no training, no mere experience of a few years can match the sense of ease and familiarity that comes from regarding space as a natural part of one's entire life.

There are two possible ways to solve these personnel problems, and probably both will be used. The first is to set up a space academy. It would offer full scholarships to selected space cadets in a program leading to the degree of Bachelor of Science. In return, the students would agree to spend the first five years of their careers with the space program. This, of course, is nothing more than what we have today in the Coast Guard and merchant marine academies and in the three academies for the military services.

It is an instructive and mind-stretching exercise to imagine what the U. S. Space Academy would be like. How strong would be the emphasis on the liberal arts and on traditional subjects like astronautics, electronics, robotics? How will this school resemble or differ from the Air Force Academy or Annapolis? Will it field a football team and how good will it be?

The Space Academy would be very much on Earth, and doubtless many a congressional district will vie for its location. The same will not be true of the second approach to those personnel problems. This is the space colony.

The first space colony may have the shape and internal layout of the Stanford torus described in Chapter 3. Yet it will be but a step toward the goal of true space colonization. If the crew modules will be like quarters in a submarine or offshore oil rig, the first space colony will be like living aboard a supertanker. In today's European merchant marines it is quite common even for junior officers to have large and well-appointed cabins with carpeting and comfortable furnishings. Frequently they take their
wives along, and an approximation to normal family life is by no means unknown. A few years ago, Globtik Tankers, Ltd. went so far as to announce plans to have a school aboard one of their tankers, so that families could stay there year-round. Nor do the womenfolk spend their days looking out the porthole while waiting for hubby to come home from the engine room. On the European ships they are treated as seagoing cadets and assigned a variety of useful tasks.

So it will be when the first space colony is opened for settlement. With the Space Spider and the other construction techniques available, building it will prove straightforward, perhaps even a trifle anticlimactic. At first the people will know only (only!) that they will have much more room, greater comfort; not mere cubicles, but true homes to call their own. But they will still be dependent at first on Earth for their food and other needs, just as before. Community life will grow slowly. The all-important systems for environmental control may simply be transplants from the old crew modules.

These families, these embryonic space communities will truly be homesteaders on the space frontier. Slowly, and with many a false start, they will develop the arts of space agriculture. They will close their environmental cycles, recycling what is needed, and in time their dependence on Earth will lessen. In contrast to the cramped crew modules, from the first they will break with a space tradition dating to the earliest Vostok and Mercury capsules. They will have room enough, and more than enough; for the Stanford torus will be too large for the initial small band of no more than a few thousand. In time their numbers will grow and they will fill to its limits; but by then the next colony will be ready.

By the year 2050, give or take a few decades, all of this may come to pass. Even before the end of the present century it is quite reasonable to say that the key problem of space transportation will be solved or well on its way to solution. A century of effort in astronautics will at last culminate in standard, reliable rockets that can serve all needs. Thereafter, progress in rockets will continue, but only in the sense that there are advances in the design of automobiles and ships. The really revolutionary developments will lie in the past.

The same will be true of the techniques of space construction. Even today we can look ahead confidently to the automated equipment that will serve the building of powersats. Only slightly further ahead lie true robots and chemical plants to process material from the Moon. Continued progress in electronics and computers, and in the building of plants to extract metals from low-grade ores, will provide the solid underpinning here. As with jet aircraft, space construction will cease to be an experiment and will instead become an industry.

What may take longest to develop will be solutions to the problem of providing for thousands of people to live in space amid self-sufficiency. Space workers will be so productive, and the value of their work so great, that even with a fully developed powersat program there may never be need for more than ten thousand people to live in space. The importance of their contributions to Earth's economy will be enormous, quite sufficient to justify the cost of creature comforts made on Earth. Even so, there will be ample reason to seek to develop space agriculture and to close the loops in their life-support systems to permit recycling of materials. [Author's footnote: Descriptions of space agriculture and closed-cycle space ecological systems, as well as of the architecture and furnishing of homes in a space colony, ar in my earlier book Colonies in Space.] A population of ten thousand can be supplied by rocket, but the effort would amount to virtually a continuous Berlin Airlift. That airlift succeeded in supplying Berlin under a Soviet blockade in 1948-49, but the effort proved quite taxing to our Air Force. Surely the presence of large space populations will stimulate much attention to promoting their independence from such large-scale resupply and to producing from space resources as much as possible of what people will need to live in comfort.

In the colony they will grow gardens and set up parks where they can pursue their friendships and loves. In a decade or so, Earth will be like Europe to many in the U.S.—a fascinating and richly rewarding place to visit, but not a place to live. Space will have lost its terrors, even its inconveniences; it will be comfortable and familiar. It will be the place where people have their jobs, their homes, their school, their lives. Space will no more be a place merely for the venturesome, for the explorers and pioneers. It will be home.